Stabilization of hydroxy benzenoid compounds and tetravalent sulphur compounds against metal catalysts



Patented Sept. 13, 1938 UNITE STATES ATENT OFFIQE COMPOUNDS AND TETRAVALENT SUL- PHUR COMPOUNDS AGAINST IWETAL OAT- ALYSTS Morris S. Kharasch, Chicago, Ill., assignor to Eli Lilly and Company, Indianapolis, Ind., a corporation of Indiana No Drawing. Application May 14, 1934, Serial No. 725,483

32 Claims.

It is the fundamental object of my invention to stabilize more effectively than has heretofore been done certain very easily oxidized benzenoid compounds, particularly those containing two negative substituents in ortho and para positions on the aromatic nucleus.

By negative substituents, I mean aminogroups or alkyl or aryl-substituted-aminogroups, or hydroxy groups, or radicals containing characteristic groupings of one or more of these groups.

It is a further object of my invention to pro-.

duce certain stabilized and stable tetravalent-sulphur salts, by which term I include sulphites and hyposulphites; which in turn will serve as stabilizers for the benzenoid compounds above referred to and for other things, in addition to being stable themselves for such uses as they may serve.

It is well known that certain benzenoid compounds, such as o-aminophenol, p-aminophenol, p-phenylenediamine, catechol, hydroquinone, metal, and epinephrin, oxidize very rapidly under certain conditions, especially in solution, and more especially in neutral and alkaline solution and indeed at any pH on the alkaline side of about pH 6; and that the oxidation increases under the action of heat and light. This oxidation is due to oxygen of the air. No water solutions which are stable at room or elevated temperatures have been prepared of these compounds.

It is also known that a certain stabilization of such benzenoid compounds, even in water solution, can be obtained by adding sodium sulphite, which preferentially takes up the oxygen. Sodium sulphite, however, is very sensitive to catalytic oxidation by oxygen in the presence of certain metal ions; chiefly copper, but also manganese and iron in the order named. Since it is substantially impossible to prepare either sodium sulphite or the benzenoid compounds free from these metal catalysts, which are cataiytically eiTective in infinitesimal amounts, the value of sodium sulphite in stabilizing these benzenoid compounds is only temporary.

Thus one way of achieving stabilization of the benzenoid compounds mentioned above resolves itself into the production of a stabilized or stable sulphite; so that such stabilized or stable sulphite may be added to the benzenoid compounds referred to, to stabilize them in turn. I

I have discovered both how to stabilize known tetravalent-sulphur salts, such as sodium sulphite, sodium hyposulphite (Na2SzO4, commonly known in the trade as sodium hydrosulphite), and others; and also how to produce certain inherently stable tetravalent-sulphur salts, both sulphites and hyposulphites, which are new. By such stabilized or stable tetravalent-sulphur salts I can produce an efi'ective and relatively permanent stabilization of the easily oxidized benzenoid compounds above referred to. I V i Stabilized and stable tetravalent-sulphur salts and their production are included in the generic subject-matter of my copending application Serial No. 725,482, filed May 14, 1934; and the present application is directed to them specifically; as well as to the stabilization of benzenoid compoundsby them. 1

Broadly speaking, my stabilization of tetravalent-sulphur salts, whether of an alkali-metal sulphite or hyposulphite or by the production of an inherently stable sulphite or hyposulphite, is by having an aliphatic 1,2-diamine present, either as a-separate added ingredient, in addition to the sulphite or hyposulphite, or as the basic part of the sulphite or hyposulphite or of some co-present substance. That is, from a generic standpoint, the aliphatic diamines may be either added ingredients initially separate from the tetravalentsulphur salts, such as the sulphite or hyposulphite, and either diamines per se or parts of compounds which contain such diamines, or may be initially part of the tetravalent-sulphur salt, as by being in combination therewith. However, I deem it preferable that the diamines, whether present per se or as part of a co-present compound, shall be separate ingredients added to the tetravalentsulphur salts, and some of my claims are directed to that preferred embodiment. Therefore, when in my claims I state merely that a diamine is present in the solution I intend to include all of these situations, because they are in effect in the same generic class; and when I intend to specify that the diamine is a separate added ingredient I specifically so state.

Various aliphatic diamines, unsubstituted or substituted, may be used for obtaining the stabi1- (OZ. iAJWlIUOHlUNZiY nus UHRJU iz'ed or stable tetravalent-sulphur salts. Among TABLE II them are the following:

a. 1,2-ethylenediamine;

b. 1,2-propylenediamine;

c. N-ph'enylethylenediamine, represented by the formula:

d. 1,2-butylenediamine;

e. 1,3-propylenediamine;

f. Condensation products of such diamines with aldehydes; and

g. Salts of such diamines, especially with weak acids.

Of these various aliphatic diamines, I prefer the 1,2-diamines, especially 1,2-ethylenediamine and 1,2-propylenediamine.

Relative effects of copper, manganese, and iron on rate of oxidation of sodium sulphite, alkalinized with sodium hydroxide and with 1,2-ethylenediamine respectively Concentration of sodium sulphitel: 1000.

Concentration of sodium hydroxide, when used, is to give pH 9.

Concentration of ethylenediamine, when used, is 5 drops per 500 cc., which gives in excess of pH 9.

Iodine titre is given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is 10.2 cc.

The measure of deterioration of sulphites, by reason of oxidation, can be followed by their loss in iodine titre; and the measure of stabilization by relative constancy in iodine titre.

The stabilization of sodium-sulphite solutions against metal catalysis by added 1,2-ethylenediamine is shown in the following Tables I and II:

TABLE I Stabilization of sodium sulphite solutions by the addition of 1,2-ethylenediamine Concentration of sodium sulphite-1:1000.

Concentration of added copper ions, when copper is added1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is $0.2 cc.

Iodine titre Added metal ions Sodium sulphite solution Original After 20 hours With added NaOH. 2. 43 0.10 None.

With added ethylenediamme. 4. 59 4.

With added N e011. 4. 30 0. 06 Cu++ I:200,000.

With added ethylenediamine. 4. 45 4. 30

(After 67 hours) With added NaOH. 3. 41 1. 13 Mn" 11200.000.

With added ethylenediamine. 4. 37 3. 87

With added NaOH. 2. 70 0. 96 Fe 1:50.000.

With added ethylenediamine. 4. 34 4. 31

The stabilization of sodium sulphite by added 1,2-propylenediamine and by added N-phenylethylenediamine, in contrast to that produced by ethanolamine (which also has some stabilizing effect), is shownin the following Table III:

TABLE D1 Stabilization of sodium sulphite solutions by the addition of ethanolamine, 1,2-p1opylenediamine, and N-phenylethylenediamine Concentration of sodium sulphite-'-1: 1000.

Concentration of added copper ions, when copper is added--1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per cc. of sodium-sulphite solution. The accuracy of the iodine titrations is :0.2 cc.

Iodine titre Ethylenediamine added Solution Orig- Lateraiter After the] time indicated days Sodium sulphite. 4. 54 2.91 (2 hrs.)

0.00 (3 days) None.

Sodium sulphite-l-copper sulphate. 4. 45 0.30 (8 hrs.)

Sodium sulphite+Na0H to give 3. 74 1.68 (2 hrs.)

pH 9. 0.00 (2 days) N one.

Sodium sulphite+Na0H to give 3.28 0.00 (2 days) pH 9+copper sulphate.

Sodium sulphite+N H 011 (5 4. 33 3.86 (4 hrs.)

drops per 500 00.). 2.27 (22 hrs None.

. Sodium sulphite+NH 0H (5 2. 77 l 71 (4 hrs.)

drops per 500 cc.)+copper sul- 0 26 (22 hrs) phate.

Sodium sulphitc. 4. 50 4.37 (3 days) 3. 89 Ethylenediamino to give pH 9.

Sodium sulphite+copper sulphate. 4. 45 3.30 (3 days) 1.01

Ethylenediamine in excess (5 Sodium sulphite. 4. 41 4.43 (3 days) 4. 41

drops per 500 00.).

Sodium sulphite+copper sulphate. 4. 45 4.30 (3 days) 4. l9

Concentration of added stabilizer-5 drops Concentration of diamine-aldehyde concentraper 500 cc. tion products1 1000.

Iodine titre Added stabilizer Solution Original fi gl i rs iiiiirs 3281- hours N Sodium sulphite+NaOH to give pH 9. 4. 65 0. 21

one.

Sodium sulphite+NaOH to give p11 9 2. 23 1. 10

+ copper sulphate.

Sodium sulphite. 4. 05 4. 33 4. 25 4. l2 Ethanolamine.

Sodium sulphite+copper sulphate. 4. 46 3. 35 1.71 0.00

1. 2-propylene-diamine. Sodium sulphite. 4. 50 4. 53 Y 4. 37 4. 25

Sodium sulphite-l-copper sulphate. 4. 48 4. 50 4. 33 4. 10

Sodium sulphite. 4. 67 3. 92 3. l 1. 73 N -phenylethylene diamine.

Sodium sulphite+copper sulphate. 4. 40 3. l6 1. 99 0. 56

Similar effects are obtainable on other sul- Iodine titre given in cc. of 0.015N iodine soluphites. tion per cc. of sodium-sulphite solution. The ac- The stabilization of sodium hyposulphite (Na2SzO4) by ethylenediamine in the presence of copper ions is shown by the following Table IV:

TABLE IV Eflect of copper on rate of oxidationof sodium hyposulphite alkalinized with sodium hydroxide and with ethylenediamine respectively Concentration of sodium sulphitel:1000.

Concentration of added copper ions--1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium sulphite solution. The accuracy of the iodine titrations is 0.2 cc.

curacy of the iodine titrations is :0.2 cc.

Such condensation products of 1,2-diamines with aldehydes may be obtained in various ways. A convenient way is by treating an ether solu- Iodine titre After bubbling air Solution Ofi b through After standing For 2 For 5 18 hours hours. hours Sodium hyposulphite-l-CuSOvl-NaOH to give pH 9.6 4. 05 3 80 0. 0.10 Sodium hyposulphite+CuSO4+ethylenediamine to give pH 9.6 4. 08 4.07 4.0% 4. 16

This effect of aliphatic 1,2-diamines in station of the aldehyde with the desired diamine;

bilizing compounds against these metal catalysts persists in condensation products of such diamines with aldehydessuch as acetaldehyde, vanillin, salicyclic aldehyde, isobutyraldehyde, etc. This stabilization effect on sodium sulphite by these condensation products is illustrated in the following Table V.

TABLE V Stabilization of sodium sulphite solutions by condensation products of 1,2-diamines and aldehydes Concentration of sodium sulphite l:1000. Concentration of added copper ions-1:200,000.

mine probably exerts its inhibiting or stabilizing action by forming extremely stable complexes with the metallic ions, as of copper, manganese, and iron, and by thus preventing such ions from exerting their catalytic efiect.

A sulphite or hyposulphite; thus stabilizedwith an aliphatic diamine is effective to produce the desired stabilization of the easily oxidized benzenoid compounds the stabilization of which is the fundamental object of the present invention. All that one needs to do to stabilize. those easily oxidized benzenoid compounds is to add thereto a small quantity of the stabilized sodium sulphite or stabilized sodium hyposulphite, or of a stable diamine sulphite.

The following three examples indicate the stabilizing action on some benzenoid compounds by a sodium sulphite stabilized with ethylenediamine.

Example 1.--A solution of 0.1 g. p-phenylenediamine in 100 cc. of water. The solution turned dark pink within five minutes; and upon standing three or four days became intensely red, and a dark brown precipitate had settled. By contrast, in an identical solution of'0.1 g. of pphenylenediamine in 100 cc. of water in which there was also dissolved 0.4 g. of stabilized sodium sulphite (stabilized with ethylenediamine) the initially colorless solution -Wasyfound to remain substantially colorless throughout the en tire period of observation, here ten, days; -Moreover, if the solution of p-phenylenediamine in water was first prepared without the stabilized sodium sulphite, and discoloration occurred, that disooloring could be removed by adding the stabilized sodium sulphite later, up to at least four hours later; and the solution so produced was free of any appreciable color throughout a tenday period of observation. 7

Example 2.A solution of 0.1 g. hydroquinone in 100 cc. of water. The solution turned dark observation. Moreover, if the colored solution of catechol was treated with stabilized sodium sulphite, the color disappeared, and did not reappear during the periodof observation.

The following Table VI summarizes these three examples.

. TABLE VI With NazSOa sta- Solution With ordinary NazSO; bilizcd with 1, 2-

. ethylenediamine p-Ihenylenedia- Dark pink to red. S u bst a n tia ll y "n'iin'e. colorless.

Hydroquinone Dark brown. Faint brown tinge. Catechol Yellow. Colorless.

.l:.;. The following .Table'VII-illustrates the stabi lization of p-phenylenediamine by sodium sulerphitez-stabilized by propylenediamine against the cited; of copper:

diamine on p-phenylenediamine in the presence Concentratiomof sodium sulphite-4110005 1 Concentration iof pephenylenediamine-'1r1000.

Concentration of added copper ions, when copper is added--1:200,000.

Added diamine Solution Original appearance g i bi gf gfag ggg g p Phenylenediamine so- Colorless. Pink. Pink.

' ldiurfis'ulpl'zlte.

None. p-Phenylenediamine so- Colorless. Dark pink. Brown.

dium sulphite copper sulphate.

. p-Phenylenediamine 50- Colorless. Colorless. Colorless.

dium ul h e- Propylenediaminc (l drop per 100 cc.). p-Phenylenediamineso.- Pale purple: iron copper- Substantially Substantially diurn sulphite copper sulpropylenedlamine comcolorless. colorless. phate. plex formed.

within five minutes; and upon standing three. or four days became very dark brown. By contrast, in an identical solution of 0.1 g. of hydroquinone in 100 cc. of water in which there was also dissolved OA g. of stabilized sodium sulphite (here again stabilized with ethylenediamine) the. solution showed only a very faint brown tinge,-and did not become darker or otherwise change in color during the ten days of=ob5flvation Moreover, if the darlgcolored solution ,of hydroquinone, darkened by reason of; the absencemf any stabilized sodium sulphite, was later-treated with stabilized sodium sulphite, up to atwleastA hours later, the discoloration almost disappeared, and the solution became only faintly tingedwith brown, with no furthur change in color during the period of observation. b

Example 3.A solution of 0.1 g. catechol in 100 cc. of Water; The solution turned yellow on standing overnight. By contrast, in an identical solution of 0.1 g. of catechol in 10000. of water in which there was also dissolved.- 0.4:g.. of stabilized sodium sulphite -(her eagainstabilized with ethylenediamine) the solution wascolorless, and remained colorless for the ten-day period of :It isdesirable' in the case of many of the benzenoid compounds which are easily oxidized that their solutions be capable of remaining colorless; andthis has heretofore been diflicult and in many casesimpossible to effect, because the oxidation caused discoloring. The foregoing Tables VI and VII illustrate how discoloration can be largely if not wholly prevented. The same .freedom from:rdiscoloratiom may be obtainedwitn -many others of ,these benzenoid compounds by having: present my diamine-stabilized:solution of an alkali-metal tetravalent-sulphur salt. This includes not only solutions of sodium sulphite and of sodium hyposulphite with added diamines, as considered in Tables I, II, III, IV, VI, and VII, but also such solutions ofeither sodium sulphite or sodium hyposulphite stabilized with condensation products of the diamines with aldehydes, as considered in Table V, as well as solutions of stable sulphites and hyposulphites described hereinafter.

It is of especial advantage in photography to have a colorless solution, as for a developer. When an ordinary 'developer containing pphenylenediamine or hydroquinone and sodium Eflect of sulphite stabilized by propylenesulphite is allowed to stand in the air, it quickly turns brown; due to the fact that sodium sulphite is used up at a great rate, and oxidation of p-phenylenediamine or the hydroquinone takes place. If instead of ordinary sodium sulphite, my stabilized sodium sulphite (containing a small amount of ethylenediamine for instance) is used, no such change in color takes place, and the solution can be kept in the light for days without undergoing any perceptible change in color.

In the preceding Tables I to VII inclusive, and in the preceding Examples 1 to 3 inclusive, the stabilization has been initially of an existing sulphite or hyposulphite with a diamine which was not part of the saltmolecule. It is possible, however, to prepare a new and inherently stable type of tetravalent-sulphur salt-sulphite and or hyposulphitefrom the aliphatic diamines, whereby the diamine enters into the salt molecule; and to use such inherently stable diamine tetravalent-sulphur salts to produce the desired stabilization of the easily oxidized benzenoicl compounds. These diamine tetravalent-sulphur salts are stable even in the presence of the metal ion catalysts of copper, manganese, and iron, and even in a solution which is neutral or slightly alkalinea property which is unique for tetravalent-sulphur salts.

These diamine salts may be prepared in various ways. The diamine sulphites may be prepared by causing the desired diamine to react with sulphur dioxide or sulphurous acid; and the diamine hyposulphites by electrolytic reduction of the diamine sulphites.

An example of these diamine salts is ethylenediamine sulphite. It is perhaps most simply prepared by passing sulphur dioxide into either an absolute or aqueous alcoholic solution of 1,2- ethylenediamine or into an acetone solution of such diamine; upon which the salt separates in solid form.

Ethylenediamine sulphite melts at 173-175" C., with decomposition. It is white, and quite soluble in water. The water solution is about pH 6.7. The analysis of the salt for nitrogen and sulphur indicates that it contains one mole of ethylenediamine to one mole of sulphurous acid. It is quite stable against metal catalysis, and is very efiective as a stabilizer of those easily oxidizable benzenoid compounds which are unstable in the presence of ions of copper, manganese, or iron. It probably has the following formula:

Another example is propylenediamine sulphite. It may be prepared analogously to ethylenediamine sulphite; and is similar thereto in most respects. It melts at 162 C., with decomposition. It also is quite stable against metal catalysis, and effective as a stabilizer of these benzenoid compounds.

Ethylenediamine hyposulphite may be obtained by reducing ethylenediamine sulphite.

These inherently stable sulphites or hyposulphites act substantially like my stabilized sodium sulphite and hyposulphite, to stabilize such benzenoid compounds as epinephrin, amino-phenols, p -phenylenediamine, etc. I have tried ethylenediamine sulphite for all the combinations which I have enumerated for obtaining stabilization by the use of my stabilized sodium sulphite; and find that such ethylenediamine sulphite is of substantially the same effectiveness as my stabilized sodium sulphite.

This action is illustrated by the following examples:

Example 4.-A 1:10,000 solution of epinephrin was divided into two parts, and one part was treated with three moles of ethylenediamine sulphite, and the other part used for a control. On heating for ten hours at 100 C., the part containing ethylenediamine sulphite remained colorless, while the control became quite dark.

Ethylenediamine sulphite has a marked advantage in stabilizing epinephrin, because it permits the epinephrin or epinephrinchloride solution to be neutral or even slightly alkaline, instead of acid. This unique proper of maintaining epinephrin preparations stable and colorless is quite important, for it is frequently desirable to use an epinephrin which is not at the acid pH at which, for the sake of stability, it is usually necessary to maintain it.

Erample 5.-Wl1en 0.1 g. of p-phenylenediamine was dissolved in 100 cc. of water the solution turned pink within a few minutes, and upon standing for five days a dark brown precipitate settled out and the solution became intensely red and quite opaque. But when 03 g. of solid ethylenediamine sulphite was added to 0.1 g. of solid p-phenylenediamine, and the whole was dissolved in 100 cc. of water, a solution was obtained which was not only initially colorless but which remained colorless during the two weeks of observation.

Example 6.-Instead of using ethylenediamine sulphite as in Example 5, I may use 1,2-propylenediamine sulphite, and get the same results as indicated in Example 5 in the stabilization of p-phenylenediamine.

Example 7.When 0.1 g. of p-amino phenol and 0.3 g. of ordinary (unstabilized) sodium sulphite were dissolved in 100 cc. of water, the solution become dark brown immediately. However, if instead of using such unstabilized sodium sulphite I use ethylenediamine sulphite, I avoid discoloration substantially completely; for on adding 0.1 g. of solid p-amino phenol to 0.3 g. of solid ethylenediamine sulphite, and dissolving the whole in 100 cc. of water, I get only a slight discoloring of the solution, and no additional discoloring during the period of two weeks during which observations were continued. Similar re sults were obtained with N-methyl-p-aminophenol (commonly known as metal).

Example 8.-When a strong alkaline solution of hydroquinone plus unstabilized sodium sulphite (such as is used in fine grain developers) is allowed to stand in the air, it rapidly assumes a black color; and when it is used in developing, the bath becomes practically unfit for use after about the third time. On the other hand, if instead of unstabilized sodium sulphite I employ either my stabilized sodium sulphite or 1,2-ethylenediamine sulphite or 1,2-propylenediamine sulphite, a solution is obtained which not only remains lightcolored for weeks but which may also be used ten or twelve times as a developing bath. The stabilizing effect of the stable diamine sulphite is even more pronounced than that of sodium sulphite stabilized with e hylene diamine.

The various examples given of benzenoid' compounds have in general been hydroxy-substituted or amino-substituted benzenoid compounds, with the substitution in the ortho position and/or in the para position; but these examples are not intended to limit the broad aspect of my invention.

For instance, pyrogallic acid, which is oxidizable but not as readily so as some of the other substances discussed, can readily be made more stable by the use of my stabilized or stable sulphites. So can naphthalene-substituted prod ucts. So also can certain derivatives of epinephrin and of ephedrine, such for instance as nor-epinephrin or 3,4-dioxy-nor-ephedrine, the structural formulas of which are as follows:

Nor-epinephrin:

SA-dioxy-nor-ephedrine:

In other words, the examples which are given are intended to illustrate and not to limit the broader aspects of my invention.

I claim as my invention:

1. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution a tetravalent-sulphur salt which has an aliphatic 1,2-diamine present with it.

2. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution a sulphite which has an aliphatic 1,2-diamine present with it.

3. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution a hyposulphite which has an aliphatic 1,2-diamine present with it.

4. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution a sodium tetravalentsulphur salt which has present with it an aliphatic 1,2-diamine as an added ingredient uncombined with the tetravalent-sulphur salt.

5, The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution sodium sulphite which has present with it an aliphatic 1,2-diamine as an added ingredient uncombined with the sodium sulphite.

6. The process of stabilizing a solutionpf a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution sodium hyposulphite which has present with it an aliphatic 1,2-diamine as an added ingredient uncombined with the sodium hyposulphite.

7. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution an aliphatic 1,2-diamine tetravalent-sulphur salt.

8. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution an aliphatic 1,2-diamine sulphite.

9. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution 1,2-ethylenediamine sulphite.

10. The process of stabilizing a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, which consists in adding to such solution 1,2-propylenediamine sulphite.

11. A composition of matter, comprising a water solution of a tetravalent-sulphur salt, in which water solution there is present an aliphatic 1,2- diamine.

12. A composition of matter, comprising a water solution of a sulphate, in which water solution there is present an aliphatic 1,2-dia1nine.

13, A composition of matter comprising a water solution of a hyposulphite, in which water solution there is present an aliphatic 1,2-diamine.

14. A composition of matter, comprising a water solution of a sodium tetravalent-sulphur salt, in which water solution there is present an aliphatic LZ-diamine as an added ingredient uncombined with the tetravalent-sulphur salt.

15. A composition of matter, comprising a water solution of sodium sulphite, in which water solution there is present an aliphatic 1,2-diamine as an added ingredient uncombined with the sodium sulphite.

16. A composition of matter, comprising a water solution of sodium hyposulphite, in which water solution there is present an aliphatic 1,2-diamine as an added ingredient uncombined with the sodium hyposulphite.

1'7. A composition of matter, comprising a solu tion of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is a tetravalent-sulphur salt which has an aliphatic 1,2-diamine present with it.

18. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is a sulphite which has an aliphatic 1,2-diamine present with it.

19. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is a hyposulphite which has an aliphatic 1,2-diamine present with it.

A compo ition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is a sodium tetravalent-sulphur salt which has present with it an aliphatic 1,2-diamine as an added ingredient.

21. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is sodium sulphite which has present with it an aliphatic 1,2-diamine as an added ingredient.

22. A composition of matter, comprising a solution of a hydroxy-benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is sodium hyposulphite which has prescut with it an aliphatic 1,2-diamine as an added ingredient.

23. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is an aliphatic 1,2-diamine tetravalentsulphur salt.

24. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is an aliphatic 1,2-diamine sulphite.

25. A composition of matter, comprising a solution of a hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is 1 .2-ethylenediamine sulphite.

26. A composition of matter, comprising a solution of a. hydroxy benzenoid compound which is easily oxidized by oxygen of the air, in which solution there is 1,2-propylenediamine sulphite.

27. A composition of matter, comprising a solution which includes as solutes hydroquinone and a tetravalent-sulphur salt which has an aliphatic 1,2-diamine present with it.

28. A composition of matter, comprising a solution which includes as solutes hydroquinone and a sulphite which has an aliphatic 1,2-diamine present with it.

29. A composition of matter, comprising a solution which includes as solutes hydroquinone and a hyposulphite which has an aliphatic 1,2-diamine present with it.

30. A composition of matter, comprising a solution which includes as solutes a benzenoid com pound of the class consisting of o-aminophenol, p-aminophenol, p-phenylenediamine,' catechol, hydroquinone, metol, and epinephrine, and a tetravalent-sulphur salt which has an aliphatic 1,2-diamine present with it.

31. A composition of matter, comprising a solution which includes as solutes a benzenoid compound of the class consisting of o-aminophenol, p-aminophenol, p-phenylenediamine, catechol, hydroquinone, metol, and epinephrine, and a sulphate which has an aliphatic 1,2-diamine present with it.

32. A composition of matter, comprising a solution which includes as solutes a benzenoid compound of the class consisting of o-aminophenol, p-aminophenol, p-phenylenediamine, catechol, hydroquinone, metol, and epinephrine, and a hyposulphite which has an aliphatic 1,2-diarnine present with it.

MORRIS S. KHARASCH.

252. tvwiomwliiu l i 1'" I" 1 iiivi 4'. 5:0

CERTIFICATE OF CORRECTION. Patent No. 2,150,522.. September 15,- 1958.

MORRIS S. KHARASCH It is hereby certified that error appears in the, printed specificat ion of the above numbered patent requiring correction as follows: Page 1, first column, line 25, for the word "metal" read metol; page 2, first column, line 1, beginning with the syllable and words "ized or stable" strike out all to and including "sodium" in line 75, second column of page and insert instead the following ized or stable tetravalent sulphur salts. Among 'them are the following:

a. 1,2-ethylenediarnine;

b. 1,2-propylenediamine;

c. N ph'enylethylenediamine, represented by the formula:

The measure of deterioration of sulphites, by reason of oxidation, can be followed by their loss in iodine titre; and the measure of stabilization by relative constancy in iodine titre.

' The stabilization of sodium-sulphite solutions against metal catalysis by added 1,2-ethylenediamine is shown in the following Tables I and II:

TABLE I Stabilization of sodium' sulphite solutions by the addition of LZ-ethylenediamine Concentration of sodium sulphite-1: 1000.

Concentration of added copper ions, when copper is added-200,000.

Iodine titre given in do. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is ;0.2 cc.

Iodine titre Solution Ethylenediaimne added orig Lam aner After inal time indicated 10 days Sodium sulphitc. t 54 2.91 (2 hrs.)

0.00 3 days) None.

Sodium sulphite+copper sulphate. 4. 45 0.30 (8 hrs.)

Sodium sulphite-l-NaOH to give 3. 74 1.68, hrs.)

pH 9. 0.00 (2 days) None.

Sodium sulphite+Na0H to give 3. 28 0.00 (2 days) pH 9+oopper sulphate. Sodium sulphita-i-NIhOH (5 4. 33 3.86 (4 hrs.)

drops per 500 cc.). v 2.27 (22 hrs.) None.

' Sodium suiphite+NH 0H (l5 2. 77 1.71.(4 hrs.)

drops per 500 cc.)+copper 3111- 006(22 hrs.) V phate.

Sodium sulphite. 4, 50- 4.37 (3 days) 3. 89 Etbylenediamine to give pH 9.

Sodium sulphite-l-copper sulphate. 4. 45 3.30 (3 days) 1.01 ylenediemine in am (5 Bodlum sulphite. 4. 41 4.43 (3 days) 4. 41

drops per 500 00.).

Sodium sulphite+copper sulphate. 4. 45 4.30 (3 days) 4. 19

- Relative ejects of copper, manganese, and iron on 'rate of oxidation of sodium sulphite, alkalinized with sodium hydroxide and with 1,2-eth1/lenediamz'ne respectively Concentration of sodium sulphite1:1000. Concentration of sodium hydroxide, when used, is to give pH 9.

Concentration of ethylenediamine, when used, isH59drops-per 500 00., which gives in excess of p Iodine titre is given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is :0.2 cc.

The stabilization of sodium sulphite by added 1,2-propylenediamine and by added N-phenylethylenediamine, in contrast to that produced by ethanolamine (which also has some stabilizing effect), is shown in the following TableIII:

TABLE I11 Stabilization of sodium sulphite solutions by the addition of ethanolamine, 1,2-propylenediamine, and -N-phenylethylenediamine Concentration of sodium sulphite-1r1000.

Concentration of added copper ions, when copper is added1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium-sulphite solution. The accuracy ot the iodine titrations is :0.2 cc.

Concentration of added stabilizer-4 di'oP p r 500 cc Iodine um Added stabilizer Solution J Original 4"" 1% 24 hours 48 hours hours Sodium sdmmmmonwme pH 0. 4 as a 2 .Q -None.

Sodium sulphite-i-NaOH togive pH 0 2. 23 l.

+ oopper miphow.

Sodium sulphite. 4 65 l 4. 33 4. 4. 12 Ethanolamine.

Sodium sulphitai-oopper sulphate. 4. 46 3. 1. 71 0.00 1. 2-propylenodiamina. Sodium sulphite. 4. 50 4. 53 4. 37 4. 25

Sodium sulphite+oopper sulphate. 4. 48 4. 50 I 4. 33 4. l0

' Sodium sulphite. 4. 67 3.92 3. l0 1. 73 N -phenylethylene diamine.

Sodium sulphite+copper sulphate. 4. 3. 16 1. 99 0. 58

252.. con/wosmoms. I t xi I in tijf Similar eifects are obtainable on other sulphites.

The stabilization of sodium 'hyposulphite (Na2S2O4) by ethylenediamine in the presence of 1 copper ions is shown by the following Table IV:

TABLE IV Eflect of copper on rate of oxidation of sodium .hyposulphite alkalinized with sodium hydroxzde and with ethylenedz'amine respectively Concentration of sodium sulphitel:l000.

Concentration of added copper ions-1:200,000.

Iodine titre given in cc. of 0.015N iodine solution per 5 cc. of sodium sulphite solution. The accuracy of the iodine titrations is $0.2 cc.

Iodine titre I i Arte: bubbling air Solution ,through- Alter standing For 2 For 5 18 hours hours hours Sodium hyposulphite-i-CuSOi+NaOH to give pH 9.6 4.05 3.80 0.10 0. Sodium hyposulphite-i-CuSprl-othylenediamine to give pH 9.6 .i 4. 08 4. 07 4. 04 4.16

TABLE V Stabilization of sodium sulphite solutions by condensation products of 1,2-diamines and aldehydes Concentration 01' sodium sulphite-1:1000. Concentration of added copper ions-1:200,000.

Concentration of diamine-aldehyde concentration products-#1000.

Iodine titre given in cc. of 0.015N iodine solutlon per 5 cc. of sodium-sulphite solution. The accuracy of the iodine titrations is :0.2 cc.

Iodine titre Solution Origi- After 11 hours Sodium sulphite 4. 20 0. 10 Sodium sulphite+condensstion product oiethylenediamiua with acetaldehyde 5. i0 4.

Sodium sulphite l-oondeusation 5651565 b'r'b'rb pylenediaminc with salicylic aldehyde 4. 4. 34

zz colv;Positions.

Such condensation products of 1,2-diamines with aldehydes may be obtained in various ways. A convenient way is by treating an ether solution of the aldehyde with the desired diamine, such as ethylenediamine. In some cases a solid separates out, as in the case of propylenediamine with salicylic aldehyde. This last-mentioned compound is a bright yellow solid, which melts .at 118 -123 C. Ethylenediamine and 2110 aldehyde also yield a bright yellow solid, which melts at about 125 C. Ethylenediamine and acetaldehyde yield. a white solid, which melts at about 108 C.

In all of these stabilizations, the aliphatic'diamine probably exerts its inhibiting or stabilizing action by forming extremely stable complexes with the metallic ions, as or copper, manganese, and iron, and by thus preventing such ions from exerting their catalytic effect.

A sulphite or hyposulphite thus stabilized with an aliphatic diamine is eflective to produce. the desired stabilization of the easily oxidized benzenoid compounds the stabilization-of which is the fundamental object of the present invention. All that one needs to do to stabilize those easily oxidized benzenoid compounds is to add thereto a small quantity of the stabilized sodium sulphite or stabilized sodium hyposulphite, or of a stable diamine sulphite.

The following three examples indicate the stabilizing action on some benzenoid compounds by a sodium sulphite stabilized with ethylenedlamine.

Example 1-. -A solution of 0.1 g. p-phenylenediamine in 100 cc. of waterl The solution turned dark pink within five minutes; and upon standing three or four days became intensely red, and a dark brown precipitate had settled. By contrast, in an identical solution of 0.1 g. of pphenylenediamine in 100 cc. of water in which there was also dissolved 0.4 g. of stabilized sodium sulphite (stabilized with ethylenediamine) the-initially colorless solution was found to remain substantially colorless throughout the entire period of observation, here ten days. Moreover, if the solution of p-phenylenediamine in water was first prepared without the stabilized sodium sulphite, and discoloration occurred, that discoloring could be removed by adding the stabilized'sodium sulphite later, up to at least four hours later; and the solution so produced was free of any appreciable color throughout a tenday period of observation.

Example 2.--A solution of 0.1 g. hydroquinone in 100 cc. of water. The solution turned dark within five minutes; and upon standing three or four days became very dark brown. By contrast, in an identical solution of 0.1 g. of hydroquinone in 100 cc. of water in which there was also dissolved 0.4 g. of stabilized sodium sulphite (here again stabilized with ethylenediamine) the solu tion showed only a very faint brown tinge, and did not become darker or otherwise change in color during the ten days of observation. Moreover, if the dark-colored solution of hydroquinone, darkened by reason of the absence of any stabilized sodium sulphite, was later treated with stabilized sodium-sulphite, up to at least 4 hours later, the discoloration almost disappeared, and the solution became only faintly tinged with brown, with no furthur change in color during the period of observation.

252.. @QMPQSUUNZF. QFQSS 4 (5) Example 3.?A solution of 0.1 g. catechol in 100 cc. of .water. The solution turned yellow on standing overnight. By contrast, in an identical solution of 0.1 g. of .catechol in 100 cc. of water in which there was also dissolved 0.4 g. of stabilized sodium sulphite '(here again stabilized with ethylenediamine) the solution was colorless, andremainedcolorless for the ten-day period of observation. Moreover, if the colored solution of cateohol was treated with stabilized sodimn sulphite, the color disappeared, and did not reappear during the period of observation. v

The following Table VI summarizes these three examples.

Eflect of sodium sulphite stabilized by ethylenediamine on certain easily oxidized benzenoid compounds The extent of discoloration indicates the extent of decomposition.

Observations after standing in the light at room temperature.

- With NmSOz sta- Solution With ordinary NmSO: bllized with 1,- 2-

ethylenediamine p-Phenylenedia- Dark pink to red. Substantially mine. colorless.

Hydroquinone Dark brown. Faint brown tinge Catechol Yellow. Colorless.

The following Table VII illustrates thestabi- .iization of p-phenylenediamine by sodium sulphite stabilized by propylenediamine against .the eilfeet of copper:

. TABLE VII Eflect of sodium sulphit'e stabilized, by propylenediamine on p-phenylenediamine in the presence f pp r Concentration of sodium sulphlte-4: 1000. Concentration of p-phenylenediamine-l: 1000. Concentration of added copper ions, when copper is added-1:200,000.

Added diamine Solution Original appearance g g si sf gfig ggg fg p-Phenylenediamine so- Colorless. Pink. Pink.

dium sulphlto.

None. p Phenylenediamlne so- Colorless. Dark pink. Brown.

' dium sulphite copper sulphate. p-Phenylenodlamine so- Colorle. Colorless. Colorless.

dium sulphite. Propylenediamine (1 drop per 100 cc.). p-Phenylenedismine so- Pale purple: iron oopper- Substantially Substantially dium sulphite copper sulpropylenediamme oomcolorless. colorless. phate. plex formed.

It is desirable in the case of many of the benzenoid compounds which are easily oxidized that their solutions be capable of remaining colorless; and this has heretofore been diflicult and in many cases impossible to effect, because the oxidation caused discoloring The foregoing Tables VI and VII illustrate how discoloration can be largely if not wholly prevented. The same freedom from discoloration may be obtained with many others of these benzenoid compounds by having present my diamine-stabilized solution of 252. COMPOSITEONS,

Qrcss Refers-x6e mm, W

page 5, first column, line 17, strike out "and" before "or";1ine

55 n the formula, for

for "prope read property;- line 1 2, f "become" read line 16,

a read became; line 55, for "metal" read metol; page 6, second column, line 15, and page 7, second column, line 1].?12, claims l2 and 51 respectively, for "sulphate" read sulphite; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 2l th day of January, A.D. 1959.

(Seal) Henry Van Arsdaile Acting Commissioner of Patents. 

